The Ras family small GTPases are molecular switch involved in controlling a wide range of cellular activities, including proliferation, growth, morphology, migration, intracellular trafficking, nuclear import/export. Post-translational modifications of the C-terminal CAAX motif are important for membrane association and biological functions of many Ras family proteins. Of particular importance is the isoprenylation of C-terminal cysteine in the CAAX motif. Isoprenylation is also present in many other proteins and is essential for their cellular functions. GCN2 is a multi-domain protein kinase involved in nutrient sensing and translation regulation. Our preliminary studies indicate that GCN2 affects the post-translational modifications of Ras and Rheb. The major goal of this proposal is to determine the molecular mechanism of GCN2 in regulation of the post-translational modifications and biological functions of the Ras family GTPases. Biochemical, cell biological, and genetic approaches will be used to achieve our goals. PUBLIC HEALTH RELEVANCE: Ras is the most frequently mutated oncogene in human cancer. The Ras family GTPases regulate normal cell growth but dysregulation can cause diseases, such as cancer. Our goal is to understand how Ras function is regulated. These studies may lead to new therapeutic treatment for cancer.